An airbag module includes an airbag cushion, an inflator and a housing. The inflator injects gas into the airbag cushion when a vehicle is in collision, so that the airbag cushion is inflated and deployed. The housing houses the airbag cushion, which is folded before deployment, and the inflator. When the airbag cushion is deployed from the housing, the airbag cushion forms a hard chamber and a soft chamber that are defined by a partition. The hard chamber is supplied with gas by the inflator and is positioned in the upper front of the airbag cushion. The soft chamber is supplied with gas by the hard chamber via a connecting hole formed in the partition and is positioned in the rear of the airbag cushion. A vent hole for exhausting gas to the outside is formed in the soft chamber.